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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
</body>
<script>
    //判定成绩甲（>90）乙(>80) 丙(>70) ,不及格，控制台打印
    //var chengji = prompt();
    /*var chengji = 89;
    if(chengji>=90&&chengji<=100){
        console.log('成绩为甲等');
    }else if(chengji>=80&&bhengji<90){
        console.log('成绩为乙等');
    }else if(chengji>=70&&bhengji<80){
        console.log('成绩为丙等');
    }else {
        console.log('成绩为不合格');
    }*/
    let score = prompt();
    let nun = Number(score);
    switch(nun){
        case 90:
            console.log('甲等');
            break;
        case 80:
            console.log('乙等');
            break;
        case 70:
            console.log('丙等');
            break;
         default:
            console.log('不合格');
            break;
    }
</script>
</html>